Scalable spine nodes with partial replication of routing information in a network environment

ABSTRACT

Embodiments are provided for partially replicating endpoint routing information, and comprise calculating a first shard interval of a key space based, at least in part, on capacities of a plurality of spine nodes in a network fabric. Embodiments also include mapping the first shard interval to a first spine node of the plurality of spine nodes, communicating shard mapping information associated with the mapping to a set of leaf nodes in the network fabric, and populating an endpoint repository in the first spine node with routing information for one or more endpoints corresponding to the first shard interval. More specific embodiments include calculating respective shard intervals for other spine nodes of the plurality of spine nodes based, at least in part, on the capacities of the plurality of spine nodes. In specific embodiments, the calculating the first shard interval is based, in part, on one or more dynamic parameters.

TECHNICAL FIELD

This disclosure relates in general to the field of networking, and moreparticularly, to scalable spine nodes with partial replication ofrouting information in a network environment.

BACKGROUND

Networking architectures have grown increasingly complex incommunication environments. Traditional hierarchical data centernetworks are built in layers that resemble a hierarchical tree. Ahierarchical tree architecture typically has an access layer at thebottom of the tree, an aggregation layer in the middle of the tree, anda core layer at the top of the tree. More recently, data centers havebeen implementing a leaf-spine hierarchical network architectures. Inleaf-spine networks, a switching fabric provides an access layercomprising multiple leaf switches that are typically fully meshed tomultiple spine switches. The leaf switches provide access to theswitching fabric for endpoints at the bottom of the tree such asservers, firewalls, loadbalancers, appliances, routers (e.g., to othernetworks), etc. Each spine switch maintains routing information for allendpoints. The routing information is maintained in the switch processmemory and also in a layer 3 (L3) routing lookup table. A fullypopulated switching fabric may contain millions of endpoints. Thus, theability to provide efficient and scalable leaf-spine hierarchicalnetworks can present significant challenges for network administratorsand component manufacturers alike.

BRIEF DESCRIPTION OF THE DRAWINGS

To provide a more complete understanding of the present disclosure andfeatures and advantages thereof, reference is made to the followingdescription, taken in conjunction with the accompanying figures, whereinlike reference numerals represent like parts, in which:

FIG. 1 is a simplified block diagram of an example network with anetwork fabric providing a system for partially replicating endpointrouting information according to at least one embodiment;

FIG. 2 is a simplified block diagram of an example implementation of thenetwork with the partial replication system and the network fabrichaving three spine nodes;

FIGS. 3A and 3B are pie charts graphically illustrating shard intervalsof an example scenario according to at least one embodiment;

FIG. 4 is a simplified flowchart illustrating possible operationsassociated with the partial replication system according to at least oneembodiment;

FIG. 5 is a simplified flowchart illustrating further possibleoperations associated with the partial replication system according toat least one embodiment;

FIG. 6 is simplified flowchart illustrating further possible operationsassociated with the partial replication system according to at least oneembodiment;

FIG. 7 is simplified flowchart illustrating further possible operationsassociated with the partial replication system according to at least oneembodiment; and

FIG. 8 is simplified flowchart illustrating yet further possibleoperations associated with the partial replication system according toat least one embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

Overview

The present disclosure describes a partial replication system for anetwork fabric. A method is provided in one example and includescalculating a first shard interval of a key space based, at least inpart, on capacities of a plurality of spine nodes in a network fabric.The method also includes mapping the first shard interval to a firstspine node of the plurality of spine nodes, communicating shard mappinginformation associated with the mapping to a set of leaf nodes in thenetwork fabric, and populating an endpoint repository in the first spinenode with routing information for one or more endpoints corresponding tothe first shard interval.

In specific embodiments, the method further includes determining acapacity of the first spine node and receiving capacity informationindicating one or more other capacities for one or more other spinenodes of the plurality of spine nodes. In further specific embodiments,the method includes receiving a packet en route to a destinationendpoint, identifying, if the destination endpoint does not correspondto the first shard interval, a second spine node mapped to a secondshard interval, and forwarding the packet to the identified second spinenode, where the destination endpoint corresponds to the second shardinterval.

Yet further embodiments include calculating one or more other shardintervals for each one or more other spine nodes of the plurality ofspine nodes based, at least in part, on the capacities of the pluralityof spine nodes. In this embodiment, the first shard interval and the oneor more other shard intervals may be assigned to the plurality of spinenodes in numerical sort order of tunnel endpoint Internet Protocol (IP)addresses of the plurality of spine nodes. In yet another embodiment,the method includes mapping at least one backup shard interval to thefirst spine node, where the at least one backup shard interval includesat least a portion of another shard interval mapped to another spinenode. Each key of the shard interval may be included in one or morebackup shard intervals mapped to one or more other spine nodes based ona replication factor.

In at least some embodiments, a hashing algorithm applied to a uniqueidentifier of any one of the one or more endpoints corresponding to thefirst shard interval generates a key that is included in the first shardinterval. Also, the shard mapping information may be communicated out ofband to the set of leaf nodes in the network fabric. At least someembodiments include dynamically recalculating the first shard intervalto determine an updated first shard interval based on the capacities ofthe plurality of spine nodes and one or more dynamic parameters of atleast one spine node of the plurality of spine nodes. The one or moredynamic parameters may include a load of one or more of the plurality ofspine nodes.

Some or all of the elements, operations, and features may be included inrespective systems, apparatuses, and devices for performing thedescribed functionality. Furthermore, some or all of the features may beimplemented in at least one machine readable storage medium.

Description of Embodiments

Turning to FIG. 1, FIG. 1 is a simplified block diagram of an examplenetwork 10 with a network fabric 15 providing a system for partiallyreplicating endpoint routing information according to at least oneembodiment. Network fabric 15 includes spine nodes 20(1)-20(K) and leafnodes 30(1)-30(N), which are fully meshed. Typically, the total numberof spine nodes is less than the total number of leaf nodes in a networkfabric. In at least one embodiment, spine node 20(1) can include anendpoint synchronization protocol 22(1), a negotiation module 24(1), anendpoint proxy module 26(1), a shard mapping table 23(1) and an endpointrepository 25(1). Spine node 20(1) may also include other componentssuch as one or more memory elements 27(1), one or more processors 29(1),one or more network interface cards and ports (not shown), and any otherhardware (or software) to facilitate the operations thereof. Other spinenodes in the network fabric (e.g., spine nodes 20(2)-20(K)) may have thesame or similar configurations (e.g., endpoint synchronization protocols22(2)-22(K), negotiation modules 24(2)-24(K), endpoint proxy modules26(2)-26(K), shard mapping tables 23(2)-23(K), endpoint repositories25(2)-25(K), memory elements 27(2)-27(K), processors 29(2)-29(K), etc.).In some example network fabrics, however, endpoint repositories25(1)-25(K) may have varied memory capacities.

Leaf nodes 30(1)-30(N) provide access for their respective endpoints40(1)-40(Z) to fabric network 15, which enables communication betweenendpoints 40(1)-40(Z). In at least one embodiment, leaf node 30(1) caninclude an endpoint synchronization protocol 32(1), a forwarding module34(1), a shard mapping table 33(1), and a local endpoint repository35(1). Leaf node 30(1) may also include other components such as one ormore memory elements 37(1), one or more processors 39(1), one or morenetwork interface cards and ports (not shown), and any other hardware(or software) to facilitate the operations thereof. Other leaf nodes inthe network fabric (e.g., leaf nodes 30(2)-30(N)) may have the same orsimilar configurations (e.g., shard mapping tables 33(2)-33(N), localendpoint repositories 35(2)-35(N), memory elements 37(2)-37(N),processors 39(2)-39(N), etc.).

Where appropriate herein, endpoints 40(1)-40(Z) are referred tocollectively as ‘endpoints 40’, spine nodes 20(1)-20(K) are referred tocollectively as ‘spine nodes 20’, and leaf nodes 30(1)-30(N) arereferred to collectively as ‘leaf nodes 30’. Similarly, other elementsin spine nodes 20 and leaf nodes 30, such as endpoint synchronizationprotocols 22(1)-22(K), shard mapping tables 23(1)-23(K), negotiationmodules 24(1)-24(K), endpoint repositories 25(1)-25(K), endpoint proxymodules 26(1)-26(K), memory elements 27(1)-27(K), processors29(1)-29(K), forwarding modules 32(1)-32(N), shard mapping tables33(1)-33(N), local endpoint repositories 35(1)-35(N), memory elements37(1)-37(N), and processors 39(1)-39(N), may be similarly referencedwhere appropriate. Also, for ease of reference, in some instances spinenodes may be referred to as ‘spines’ and leaf nodes may be referred toas ‘leaves’.

For purposes of illustrating certain example techniques of networkfabric 15, it is important to understand the communications that may betraversing the network and the protocols used in effecting suchcommunications. The following foundational information may be viewed asa basis from which the present disclosure may be properly explained.

In a leaf-spine hierarchical data center network architecture, each leafnode may have a local endpoint repository and a routing lookup table. Arouting lookup table may be stored in a ternary content-addressablememory (TCAM) and can be derived from the endpoint repository. A localendpoint repository, which is also referred to as a routing informationbase (RIB), of a leaf node may only include mapping information oflearned endpoints behind that leaf node. A leaf node RIB can learnmapping information for each endpoint in the network and the address ofthe leaf node (or tunnel endpoint) that the endpoint sits behind.

Leaf nodes, however, may not always have a fully replicated RIB. This isparticularly true in the beginning after a leaf node is booted (orrebooted), when the RIB in the leaf node is still being populated. Inthis case, when the leaf node receives unknown unicast traffic, if adestination address (e.g., Media Access Control (MAC)/Internet Protocol(IP)) in a packet is missing from the leaf node's local routing lookuptable, the leaf node relies on an endpoint proxy residing in a spinenode to forward this unknown unicast traffic to the egress leaf node. Ina full mesh leaf-spine network, a leaf node may send unknown unicasttraffic to any spine node via a spine node anycast address. Thus, thetraffic may be sent to the closest spine node without regard to whatrouting information is maintained by the spine node. Therefore, eachspine node has to maintain routing information in its process memory forall endpoints in the network, in addition to a layer 3 (L3) routinglookup table.

A fully populated network fabric may contain millions of endpoints. Thiscan pose significant performance and scalability challenges over centralprocessing unit loads, memory utilization, and network bandwidth. Inaddition, it can be difficult to ensure fast convergence and consistencyfor such a huge routing information repository across all spine nodes.The capacity of a network is limited by the capacity of the leastcapable spine node (hotspot) in the network fabric. For example, if anetwork fabric has one spine node that can process a maximum of 100Kendpoints, then the endpoint RIB replicated in all spine nodes of thenetwork fabric will be limited to routing information for 100K endpointseven if other spine nodes have more capacity and can processsignificantly more endpoints (e.g., 1.2 million endpoints).Consequently, the less capable spines may become a ‘hotspot’, while thelarger spine nodes are idle or not fully utilized. For virtual switchnetworks containing software endpoint proxies, similar challenges exist.

Embodiments of a network with a network fabric, as described herein, canresolve the aforementioned issues (and more) by providing a system forpartial replication of endpoint routing information, where each spinenode maintains a subset of endpoint routing information for the network.More specifically, endpoint routing information of the network isdivided and distributed across multiple spine nodes using a shardingprotocol and a configurable replication factor. The sharding protocolcan divide and distribute endpoint routing information based on load,capacity, and/or fault state of spine nodes in at least one embodiment.Furthermore, the sharding protocol can be applied before endpointrouting information is learned in a network fabric, and may also besubsequently applied dynamically based on various triggers in thenetwork (e.g., fault state changes, new spine node added to networkfabric, spine node removed from network fabric, load changes, etc.). Ashard mapping table can be generated and stored in the spine nodes andcan include shard mapping information that indicates which spine nodescan provide routing information for which endpoints. The shard mappinginformation can be propagated to leaf nodes in the network fabric by anout of band controller or a control plane protocol. Propagating theshard mapping information enables the leaf nodes to forward unknownunicast traffic to the correct spine node without additional data pathperformance penalties.

Several advantages can be achieved by offering a system for partiallyreplicating endpoint routing information in the spine nodes of a networkfabric. First, a partial replication system can significantly improvescalability and convergence of spine nodes, by reducing the networkbandwidth, central processing unit loads, and process and hardwarerouting lookup table memory requirements needed to maintain fullreplication of endpoint RIBs on each spine node. With a partialreplication system, the maximum number of endpoints a network fabric canprocess scales linearly with the number of spine nodes. Thus, the fabricendpoint capacity can be significantly increased because more endpointroutes can be maintained using partial endpoint repository replication.In addition, spine heterogeneity can be accommodated in a networkfabric, because the network fabric is not limited to the capacity of theleast capable spine node. By way of example, a network fabric can handlemore than 1.2 million endpoints when the network fabric includes a spinenode, which is capable of handling 1.2 million endpoint routes whenfully loaded, along with less capable spine nodes. Another advantage ina partial replication system includes sharding negotiation between spinenodes that can be dynamic and that can be based on load, capacity, faultstate, other static or dynamic parameters, or any suitable combinationthereof. Moreover, the initial sharding negotiation and subsequentdynamic sharding negotiation can remain mostly transparent to leaf nodesby advertising shard interval ownership (e.g., shard mappinginformation) via link layer protocols or fabric control protocols.

Turning to FIG. 1, a brief description is provided about some of thepossible infrastructure that may be included in network 10. Network 10represents a series of points or nodes of interconnected communicationpaths for receiving and sending communications that propagate throughthe network. Elements of FIG. 1 may be coupled to one another throughone or more virtual or physical interfaces employing any suitableconnection, which provides a viable pathway for electroniccommunications. The teachings of this disclosure can be implemented inmany different types or topologies of networks including, but notlimited to, a local area network (LAN), wireless local area network(WLAN), Intranet, Extranet, virtual local area network (VLAN), virtualprivate network (VPN), virtual extensible local area network (VXLAN),virtual private LAN service (VPLS), any suitable combination thereof, orany other appropriate architecture or system that facilitatescommunications in a network environment.

Communications in network 10 are referred to herein as ‘network traffic’or ‘traffic’, which may be inclusive of packets. A packet is a formattedunit of data, and can contain both control information (e.g., source anddestination endpoint addresses, etc.) and data, which is also known aspayload. A single communication from a source endpoint to a destinationendpoint may be broken up into multiple discrete packets with differentpayloads. Network traffic can be sent and received according to anysuitable communication messaging protocols. Suitable communicationmessaging protocols can include a multi-layered scheme such as OpenSystems Interconnection (OSI) model, or any derivations or variantsthereof (e.g., transmission control protocol/IP (TCP/IP), user datagramprotocol/IP (UDP/IP), etc.). Also, link layer protocols may be utilizedto facilitate communications related to the sharding protocol and otherrouting information including, but not limited to, Link Layer DiscoveryProtocol (LLDP) and Intermediate System to Intermediate System (IS-IS).

The term ‘data’ as used herein, refers to any type of binary, numeric,voice, video, textual, or script data, or any type of source or objectcode, or any other suitable information in any appropriate format thatmay be communicated from one point to another in electronic devicesand/or networks. Additionally, advertisements, messages, requests,responses, replies, queries, etc. can be forms of network traffic.

Spine nodes 20 and leaf nodes 30 are virtual or physical switches orother network elements that include switching functions and thatfacilitate electronic communication in a given network. As used herein,the term ‘network element’ is meant to encompass routers, switches,wireless access points (WAPs), gateways, bridges, loadbalancers,appliances, firewalls, servers, processors, modules, or any othersuitable device, component, element, proprietary appliance, or objectoperable to exchange information in a network environment. A networkelement may include any suitable hardware, software, components,modules, interfaces, or objects that facilitate the operations thereof.This may be inclusive of appropriate algorithms and communicationprotocols that allow for the effective exchange of data or information.Spine nodes 20 and leaf nodes 30 can be layer 2 (L2) or layer 3 (L3)devices such that the links between the spine and leaf layers of thearchitecture are either switched (L2) or routed (L3). In addition, in atleast one implementation, network fabric 15 may implement a Top of Rack(ToR) network architecture for leaf nodes 30.

In at least one embodiment, endpoints 40 are connected to network fabric15 through leaf nodes 30. Network fabric 15 facilitates communicationamong endpoints that are connected to different leaf nodes 40. Endpoints40 can be various network elements including, but not limited to,servers, firewalls, loadbalancers, appliances, wireless access points(WAPs), gateways, routers (e.g., to other fabric pods, to the Internet,etc.), and hosts.

In at least one example implementation, spine nodes 20 and leaf nodes 30include logic to achieve (or to foster) the activities that enablepartial replication of endpoint routing information in a spine layer, asoutlined herein. Note that in at least one example, each of theseelements can have an internal structure (e.g., processors 27, 37, memoryelements 29, 39, network interface cards, ports, etc.) to facilitatesome of the operations described herein. In other embodiments, theseactivities that enable partial replication of endpoint routinginformation in a spine layer may be executed externally to theseelements, or included in some other network element to achieve thisintended functionality. In at least one embodiment spine nodes 20 andleaf nodes 30 may include this logic (or reciprocating logic) that cancoordinate with other network elements in order to achieve theoperations, as outlined herein. Furthermore, one or several devices mayinclude any suitable algorithms, hardware, firmware, software,components, modules, interfaces, or objects that facilitate theoperations thereof.

Spine nodes 20 may include negotiation modules 24 to enablecommunication among spine nodes 20 to divide and distribute endpointrouting information across spine nodes 20 using a sharding protocol. Ina particular example, spine nodes 20 communicate with each other tonegotiate ownership of a key space (e.g., 32 bits). A sharding algorithmcan be used to divide a key space into a number of shard intervals thatequals a total number of spine nodes 20 in the network fabric. Eachshard interval can define a range of keys within the key space. Eachendpoint in network 10 corresponds to a key in one of the shardintervals. The shard intervals can be mapped to respective spine nodes20. In at least one embodiment, the shard intervals are assigned to eachspine node in numerical sort order of their tunnel endpoint IP (TEP IP)addresses. To provide redundancy, each spine node can be a primary ownerof one shard interval (also referred to herein as a ‘primary shardinterval’), as well as a backup owner of one or more other ‘backup shardintervals’ that belong to other spine nodes. Each spine node maintainsan endpoint repository (e.g., endpoint repositories 25) and programs ahardware routing table (e.g., TCAM) for endpoints corresponding to aprimary shard interval mapped to the spine node and for endpointscorresponding to any backup shard intervals mapped to the spine node.

The size of a primary shard interval and any backup shard intervalsmapped to a particular spine node can be determined based, at least inpart, on a total number of spine nodes in the network fabric and staticparameters such as the capacities of the spine nodes. The capacity of aspine node correlates to how many endpoint routes the spine node canmanage. The size of the primary and backup shard intervals may alsodepend on dynamic parameters. Dynamic parameters can include, but arenot limited to a current load of the spine node and/or a fault state ofthe spine node. Thus, the endpoint routes can be load-balanced acrossall operational spine nodes 20 within network fabric 15.

In at least one embodiment, the key space may be 32 bits. A unique32-bit key may be generated for each endpoint based on a uniqueidentifier of the endpoint. For endpoints attached to a layer 2 leafnode, a key corresponding to an endpoint can be generated by applying ahashing algorithm to a bridge domain (BD) and Media Access Control (MAC)address of the endpoint in order to hash the BD and MAC address into thekey space. For endpoints attached to a layer 3 leaf node, a keycorresponding to an endpoint can be generated by applying a hashingalgorithm to virtual routing function (VRF) virtual network identifier(VNID) and Internet Protocol (IP) address of the endpoint in order tohash the VRF VNID and IP address into the key space. It will be apparentthat the keys generated for the endpoints may be based on any othersuitable unique identifier of those endpoints, and the unique identifiermay be a single identifier or a combination of identifiers.

In at least one embodiment, the hashing algorithm applied to the BD andMAC address or the VRF and IP address is designed to hash into the keyspace evenly. In one example, a Jenkins hash function may be used as thehashing algorithm. The Jenkins hash functions are a collection ofnon-cryptographic hash functions for multi-byte keys. It will beapparent that other suitable hash functions may be used alternatively,depending on particular design criteria and implementations.

In at least one embodiment, primary shard intervals are assigned to eachspine node in numerical sort order of their tunnel endpoint IP (TEP IP)addresses. By way of example, consider a network fabric of 12 spinenodes of the same capacity. The spine node having the fourth largest TEPIP address can own the primary shard interval of (3*2{circumflex over( )}32/12, 4*2{circumflex over ( )}32/12]. The spine node with the fifthlargest TEP IP address can own the primary shard interval of(4*2{circumflex over ( )}32/12, 5*2{circumflex over ( )}32/12] and soon. In this example, any endpoint with a hashed key falling into theinterval (3*2{circumflex over ( )}32/12, 4*2{circumflex over ( )}32/12]has routing information that is owned by the fourth spine node (e.g., inendpoint repository of the fourth spine node and hardware routingtable/TCAM of the fourth spine node).

In a more complicated example where the capacities of the spines aretaken into consideration, the shard allocation and assignment can be afunction of the number of spines and the capacity level of each spine inthe fabric. For example, if a least capable spine is assigned a capacitylevel of 1, a spine that is two times more powerful can have a capacitylevel of 2, a spine that is four times more powerful can have a capacitylevel of 4, and so on. The primary shard can be assigned in such a waythat the spine of capacity level 4 has a shard twice the size of thecapacity level 2 spine and 4 times the size of the capacity level 1spine. The combined primary shards of all spines should cover thecomplete 32 bit key space. If a replication factor #R, is configured forthe network fabric, each spine node can be the backup owner of #Rshards. The size of each backup shard owned by a spine can be the samesize as the spine's primary shard.

One example to calculate a backup shard interval of each spine with areplication factor of 2 is demonstrated in example pie charts 300 and310 of FIGS. 3A and 3B. In primary shard pie chart 300, spine1 andspine2 own the first quarter (i.e., 12.5% each) of the key space withintervals of [0, 2{circumflex over ( )}32/8) and [2{circumflex over( )}32/8, 2{circumflex over ( )}32/4), respectively. Spine3 owns thesecond quarter of the key space with an interval of [2{circumflex over( )}32/4, 2{circumflex over ( )}32/2). Spine4 owns the second half thekey space [2{circumflex over ( )}32/2, 2{circumflex over ( )}32). Tocalculate the backup shard intervals, all primary shards can be rotated(e.g., clockwise or counterclockwise) by the biggest primary shard size.The resulting backup shards are depicted in backup shard pie chart 310of FIG. 3B. Each spine owns the rotated shard interval as their backupshard. Similarly, for a replication factor of 3, the shard pie chart canbe rotated one more time and the backup interval can be assigned. In atleast some embodiments, a single continuous range of keys within the keyspace may include a primary shard interval and one or more backup shardintervals owned by a spine node.

Shard mapping tables 23 can be provided in spine nodes 20, and shardmapping tables 33 can be provided in leaf nodes 30. Shard mapping tables23 and 33 may be stored in one or more databases, files, caches, or anyother suitable storage structure, or any suitable combination thereof.Shard mapping tables 23 and 33 may be internal to spine nodes 20 andleaf nodes 30, respectively. In some other embodiments, shard mappingtables 23 and 33 may be external (entirely or in part) to spine nodes 20and leaf nodes 30 using, for example, some network storage techniquesuch as network attached storage (NAS) or storage area network (SAN). Insome instances, shard mapping tables 23 could be consolidated in asuitable form and location to be accessible to spine nodes 20, and/orshard mapping tables 33 could be consolidated in a suitable form andlocation to be accessible to leaf nodes 30. In some other instances,shard mapping tables 23 and 33 could be consolidated in a suitable formand location to be accessible to spine nodes 20 and leaf nodes 30.

Shard mapping tables 23 and 33 can be populated with information thatindicates which spine nodes own which shard intervals. In one example,shard mapping tables 23 and 33 can include mappings between primaryshard intervals and their assigned spine nodes, and mappings betweenbackup shard intervals and their assigned spine nodes. As used herein,the term ‘mapping’ is intended to include a marking or linking technique(e.g., pointers, indexes, file names, relational databases, hash table,etc.), or any other technique that indicates a relation, association,correspondence, connection, or link between two or more ‘mapped’ items.

Spine nodes 20 can advertise shard mapping information to leaf nodes 30.Shard mapping information can be information in any suitable form thatidentifies at least one spine node and the primary and backup shardintervals it owns. In at least one embodiment, each spine nodeadvertises its own primary shard interval and backup shard interval(s)to every leaf node in network 10. This shard mapping information can becommunicated to each leaf node through an out-of-band fabric controlleror through switch control plane protocol such as, for example, linklayer discovery protocol (LLDP) or intermediate system to intermediatesystem (IS-IS) protocol. LLDP can be used to advertise the shard mappinginformation to directly connected leaf nodes via fabric ports.Alternatively, one spine node anycast address can be created for eachshard interval and propagated to leaf nodes through IS-IS protocol asroute attributes. Knowledge of the shard mapping information enablesleaf nodes 30 to forward unicast traffic to the correct spine node(i.e., the spine node that owns a shard interval corresponding to thedestination endpoint of the unicast traffic).

Spine nodes 20 can also be provided with endpoint synchronizationprotocol 22, for learning routing information of endpoints 40 andpopulating endpoint repositories 25. Endpoint repositories 25 can beprovided in spine nodes 20, and may be stored in the form of one or moredatabases, files, caches, or any other suitable storage structure, orany suitable combination thereof. In at least one embodiment, endpointrepositories 25 can each be configured as partially replicated routinginformation bases (RIBs) for network 10. A RIB can contain routinginformation for endpoints in network 10. In particular, routinginformation for an endpoint indicates which leaf node the endpoint isbehind. In embodiments disclosed herein, an endpoint repository of aparticular spine node contains routing information only for endpointscorresponding to a primary shard interval mapped to the spine node andfor endpoints corresponding to any backup shard intervals mapped to thespine node. A spine ‘owns’ the routing information of an endpoint if thespine maintains the routing information for that endpoint in the spine'sendpoint repository and hardware lookup tables (e.g., TCAM).

Routing information for endpoints 40 can be learned by spine nodes 20when leaf nodes 30 advertise or otherwise communicate information aboutnew endpoints 40 or any other endpoint for which routing information isnot available in a spine node. In at least one embodiment, endpointsynchronization protocol 22 and 32 can be provided on spine nodes 20 andleaf nodes 30, respectively, to enable this communication and learning.A control plane endpoint manager of a leaf node does not have to beaware of spine node topology in order to advertise learned endpoints.For example, when leaf node 30(1) learns of a new endpoint, leaf node30(1) may advertise the new endpoint via endpoint synchronizationprotocol 32(1) to any spine node in network fabric 15. The endpointsynchronization protocol of the receiving spine node can forward theadvertisement to the primary shard owner and backup shard owners. Forexample, if spine node 20(1) receives an advertisement, it may storerouting information for the endpoint in endpoint repository 25(1) if theendpoint corresponds to a shard interval owned by spine node 20(1).Otherwise, endpoint synchronization protocol 22(1) on spine node 20(1)can forward the endpoint advertisement to the appropriate spine. Theappropriate spine node can be identified by generating a key for theendpoint and querying shard mapping table 23(1) to identify both theshard interval that contains the key and the primary and backup spinenodes that are mapped to the identified shard interval.

Forwarding modules 34 can be provided in leaf nodes 30 for forwardingunknown unicast traffic from an attached endpoint to the appropriatespine node in network fabric 15. By way of illustration, when leaf node30(1) receives unicast traffic from an attached endpoint and the unicasttraffic contains a destination address that is not found in localendpoint repository 35(1), then leaf node 30(1) can generate a key forthe destination endpoint by hashing a unique identifier of thedestination endpoint (e.g., the BD and MAC address or the VRF and IPaddress). Shard mapping table 33(1) can be queried to identify a shardinterval that contains the key, and to identify one of the multiplespine nodes owning the identified shard interval. The unknown unicasttraffic can be forwarded to the identified spine node. However, if aspine node is not identified (e.g., shard mapping table 33(1) does notinclude a shard interval containing the key), then the unknown unicasttraffic can be forwarded to any of the spine nodes 20. The receivingspine node can then forward the unknown unicast traffic to theappropriate spine node.

Endpoint proxy modules 26 of spine nodes 20 can be provided in spinenodes 20 for forwarding received traffic to the appropriate leaf node orspine node in network fabric 15. A spine node can forward unknownunicast traffic to another spine node that owns the routing informationof the destination endpoint of the unknown unicast traffic. For example,when unknown unicast traffic is received by spine node 20(1), endpointproxy module 26(1) can generate a key for the destination endpoint ofthe unknown unicast traffic by hashing a unique identifier of thedestination endpoint (e.g., the BD and MAC address or the VRF and IPaddress). Endpoint proxy module 26(1) can then query shard mapping table23(1) to identify a shard interval that includes the key, and toidentify a spine node mapped to the identified shard interval. If theidentified shard interval does not belong to spine node 20(1) (e.g., ifthe identified shard interval is not mapped to spine node 20(1) in shardmapping table 23(1)), then the unknown unicast traffic can be forwardedto the identified spine node, which can forward the traffic to the leafnode to which the destination endpoint is connected. However, if theidentified shard interval belongs to spine node 20(1), then spine node20(1) can determine the correct routing information to the destinationendpoint (e.g., from endpoint repository 25(1), from a hardware routingtable/TCAM, etc.) and can forward the traffic based on the routinginformation.

If spine node 20(1) receives traffic other than unknown unicast traffic,then spine node 20(1) should have routing information for thedestination endpoint in endpoint repository 25(1). Endpoint proxy module26(1) can determine the correct routing information to the destinationendpoint (e.g., from endpoint repository 25(1), from a hardware routingtable/TCAM, etc.) and can forward the traffic based on the routinginformation. If the routing information is not found, then spine node20(1) can determine the appropriate a spine node mapped to thedestination endpoint of the traffic as previously described. Spine node20(1) can then forward the traffic to the identified spine node, whichcan then forward the traffic to the leaf node to which the destinationendpoint is attached.

FIG. 2 illustrates an example implementation of network 10 with networkfabric 15 having three spine nodes 20(1), 20(2), and 20(3) according toat least one embodiment. In this example, spine nodes 20(1) and 20(2)have the smallest capacity (e.g., 0.3 million endpoint routes), andspine node 20(3) has the largest capacity (e.g., 0.6 million endpointroutes). A capacity level of 3, 3 and 6 can be assigned to these spinesrespectively.

Spine nodes 20(1), 20(2), and 20(3) can negotiate with each other asindicated by shard negotiations 50(1) and 50(2), and can apply asharding algorithm to divide a 32-bit key space into three primary shardintervals, one for each spine node. Although not shown in FIG. 2, itwill be apparent that shard negotiations may occur between any two spinenodes including spine node 20(1) and spine node 20(3). The negotiationscan include periodic ping/pong beacon messages being exchanged among thespines. These messages enable each spine to know the capacity of allother spine in the fabric. Based on this knowledge, each spine canindependently calculate the shard intervals for each spine using thesame algorithm. This ensures the resulting shard mapping to be in syncacross the entire fabric. Shard mapping tables 23(1), 23(2), and 23(3)can be generated, which include information indicating which shardintervals are mapped to which spine nodes.

An example sharding algorithm as described above may determine how manyendpoint routes each spine node can efficiently manage, a size of ashard interval for each spine node, and a particular range of the keyspace for each shard interval. In addition to the static parameters likecapacity, dynamic parameters, or both may be used for thisdetermination. For example, the capacity of a spine node is a staticparameter and can be used to determine an upper limit or maximum numberof endpoints the spine node should be able to manage. Dynamic parametersmay also be considered in some scenarios, such as a current load of aspine node. For example, if a load of a spine node is too high (e.g.,above a certain threshold load), then the maximum number of endpointsallowed by the spine node's capacity may be adjusted downwardly toenable the spine node to operate more efficiently. In at least oneembodiment, shard negotiation includes spine nodes 20 communicating bothstatic and dynamic parameters to other spine nodes 20 in network fabric15 to be used by instances of the sharding algorithm.

A size of a primary shard interval for the spine node can be determinedbased, at least in part, on the number of spine nodes and their capacitylevels. For example, if spine node 20(1) is determined to be capable ofmanaging ¼ of the endpoint routes that can be maintained by all spinenodes 20, then the primary shard interval mapped to spine node 20(1) mayinclude ¼ of the key space. The hashing algorithm applied to theendpoint identifiers (e.g., BD and MAC, VRF and IP) may be configured togenerally distribute the hashed keys evenly. Thus, the shard intervalmapped to spine node 20(1) should correspond to about ¼ of the endpointsin the network.

Also, when negotiating the size of a shard interval, dynamic parameters,such as a fault state parameter, may also be considered. For example, ifa spine node goes down (i.e., crashes or otherwise stops operating),then the sharding algorithm can be dynamically re-applied, and theendpoints can be spread across the remaining, operational spine nodes.Consequently, the size of the shard intervals (and the particular rangein the key space) may be adjusted to compensate for the loss of one ofthe spine nodes.

Last, a particular range for the shard interval in the key space can bedetermined in any suitable way once the size of the shard interval isdetermined. In one example, shard intervals are assigned to spine nodes20 in numerical sort order of their tunnel endpoint IP (TEP IP)addresses. Spine nodes 20 may communicate with other spine nodes innetwork fabric 15 (e.g., during sharding negotiations) to provide theirTEP IP addresses to each other.

In the example illustration of FIG. 2, the shard intervals assigned tospine nodes 20(1), 20(2), and 20(3), based on a 32-bit key space, canreflect variations in capacities. For example, the following primaryshard intervals could be assigned to spine nodes 20(1)-20(3) based onthe indicated capacities:

Spine Node Capacity Primary Shard Interval Spine node 20 (1) 0.3Mendpoint routes [0,0x40000000) Spine node 20 (2) 0.3M endpoint routes[0x40000000,0x80000000) Spine node 20 (3) 0.6M endpoint routes[0x80000000,0xFFFFFFFF]

The example above is simplified to include only primary shard intervalsmapped to spine nodes 20(1), 20(2), and 20(3). Embodiments disclosedherein, however, accommodate redundancy of endpoint routing informationin the spine nodes. Thus, one or more backup shard intervals may also bemapped to spine nodes 20(1), 20(2), and 20(3), based on a replicationfactor, #R. The replication factor #R could be configured by a user ordetermined automatically (e.g., default replication factor, networkpolicies, tenant policies) for the network fabric. In at least oneembodiment, each spine can be the backup owner of #R−1 shards and thesize of each backup shard for a spine can be the same size as thespine's primary shard. In one example, for a replication factor of two,a single continuous range of keys within the key space could include theprimary shard interval and a backup shard interval, which are owned byspine node 20(1).

Embodiments described herein enable a network fabric to support moreendpoints with less configured hardware, in addition to spineheterogeneity and faster convergence due to a distributed endpointrepository maintenance cost. For example, a network fabric with fourspine nodes that individually (or together with full replication) cansupport 600K endpoint routes, can together with the partial replicationteachings herein support 2.4M endpoint routes. Similarly, a networkfabric with four spine nodes that individually (or together with fullreplication) can support 1.2M endpoint routes, can together with thepartial replication teachings herein support 4.8M endpoint routes. Afabric pod (i.e., multiple fabric networks and corresponding endpoints)with twelve spine nodes that individually support 1.2M endpoint routes,can support up to 14.4M endpoint routes. Thus, the maximum number ofendpoint routes supported by the network fabric scales linearly with thenumber of spine nodes.

Turning to FIGS. 4-8, FIGS. 4-8 are simplified flowcharts illustratingpossible operations associated with a system for partially replicatingendpoint routing information in network fabric 15 according to at leastsome of the embodiments disclosed herein. In FIG. 4, a flow 400illustrates one or more possible operations that may be performed byspine nodes 20 of FIGS. 1 and 2. Spine nodes 20 may comprise means,including for example, processors 29, for performing such operations. Inat least one embodiment, negotiation modules 24 of spine nodes 20 areconfigured to perform, when executed by a processor, one or more of theoperations. For ease of explanation, and where appropriate, thedescription provided for flows of FIGS. 4-8 may refer to spine node20(1), leaf node 30(1), and/or endpoint 40(1), although it will beapparent that the flows of FIGS. 4-8 could involve any one or more spinenodes 20, leaf nodes 30, and endpoints 40 of network fabric 15.

Flow 400 may be initiated when spine nodes 20 need to learn endpointroutes (e.g., when spine nodes are reset or powered on). Flow 400 mayalso be initiated dynamically when some trigger indicates the shardingalgorithm is to be applied to recalculate shard intervals for networkfabric 15. In some implementations, at least some portions of flow 400may be performed by each spine node in network fabric 15.

At 402, spine node 20(1) negotiates with other spine nodes in networkfabric 15 (e.g., spine nodes 20(2)-20(K)) and applies a shardingalgorithm to a key space to calculate shard intervals for the spinenodes. More details related to applying the sharding algorithm to thekey space and negotiating with the other spine nodes will be discussedherein at least with reference to FIG. 5.

At 404, shard mapping table 23(1) may be created and stored in spinenode 20(1). Shard mapping table can be populated with informationindicating which shard intervals are owned by which spine nodes innetwork fabric 15. In at least one embodiment, primary and backup shardintervals generated for spine node 20(1) can be mapped to spine node20(1) (e.g., using a unique identifier of the spine node) in shardmapping table 23(1). Similarly, other primary and backup shard intervalsgenerated for the other spine nodes can be mapped to those other spinenodes in shard mapping table 23(1).

At 406, shard mapping information can be advertised from spine node20(1) to leaf nodes 30. In at least one embodiment, each spine nodeadvertises its own shard mapping information to leaf nodes 30. In otherembodiments, shard mapping information for multiple spine nodes 20 maybe advertised by a single spine node. In yet other embodiments, at leasttwo spines advertise the shard mapping information to different leafnodes such that all leaf nodes receive the information from at least onespine.

When dynamic re-sharding is performed (e.g., at 402), endpointrepositories 25 of spine nodes 20 may not be correctly and/or fullypopulated. This can occur when shard intervals are dynamicallyrecalculated based on some trigger such as, for example, a spine nodecrashing or otherwise ceasing to operate, a new spine node being addedto network fabric 15, a spine node being removed from network fabric 15,a spine node being replaced in network fabric 15, excessive loaddetected on a spine node, etc. In these scenarios, the ranges of theshard intervals may change for some or all of the spines. Such a changecould cause a spine node's endpoint repository (and hardware routingtable) to contain routing information for endpoints that no longercorrespond to the spine node's shard interval. Furthermore, the changecould potentially cause a spine node's endpoint repository to no longerbe fully populated with all of the endpoint routes owned by the spinenode, according to its updated shard interval.

At 408, a determination can be made as to whether endpoint repository25(1) of spine node 20(1) contains routing information that should beexcluded based on the shard interval generated for spine node 20(1). Ifendpoint repository 25(1) is determined to contain routing informationthat should be excluded, then at 410, spine node 20(1) determines whichspine nodes own the endpoint routing information that should beexcluded. Spine node 20(1) may calculate a key for the endpointassociated with the endpoint routing information to be excluded. The keymay be generated by hashing the BD and MAC address or the VRF and IPaddress of the endpoint, which may be stored in endpoint repository25(1) with the routing information. Spine node 20(1) may then queryshard mapping table 23(1) to identify the shard interval that includesthe key, and to identify the spine node mapped to the shard interval. At412, spine node 20(1) can forward the endpoint routing information tothe identified spine node. At 414, the endpoint routing information canbe deleted from endpoint repository 25(1). In at least one embodiment,operations of 408-414 (or some variation thereof) may be performed byendpoint synchronization protocol 22(1), which can sync the endpointinformation from an old master spine (e.g., spine node 20(1)) to a newmaster spine. If no master spine for the particular shard range isalive, the new master spine may request the leaf nodes to republishtheir endpoint information.

At 416, if endpoint repository 25(1) is not fully populated with all ofthe endpoint routing information for endpoints associated with its new(or updated) shard intervals, then spine node 20(1) can learn therouting information from either another spine node in network fabric 15or a leaf node or nodes to which the relevant endpoints are attached.Endpoint repository 25(1) may be populated with the learned endpointrouting information received from leaf nodes and/or spine nodes.

FIG. 5 illustrates a flow 500 of one or more possible operations thatmay be performed by spine nodes 20 of FIGS. 1 and 2, in which spinesnodes 20 negotiate with each other and apply a sharding algorithm tocalculate shard intervals from a key space. Spine nodes 20 may comprisemeans, including for example, processors 29, for performing suchoperations. In at least one embodiment, negotiation modules 24 of spinenodes 20 can be used to perform, when executed by a processor, one ormore of the operations.

At 502, spine node 20(1) receives static and dynamic parameters of otherspine nodes in network fabric 15 via, for example, ping/pong beaconmessages being exchanged among the spines. In some embodiments, spinenode 20(1) may only receive static parameters, or may only receivedynamic parameters. Static parameters can include, for example,capacities of the other spines. For example, spine node 20(1) mayreceive a static parameter from spine node 20(3) indicating its capacityallows 0.6M endpoint routes. Dynamic parameters can include, forexample, a current load and a fault state of a device. The current loadof a spine node can indicate the amount of traffic being processed bythe spine node. A fault state can indicate whether the spine node has anerror, has crashed, or is operational.

At 504, spine node 20(1) may communicate its own static and dynamicparameters to the other spine nodes in network fabric 15. In addition,the tunnel endpoint IP (TEP IP) addresses of spine nodes 20 may becommunicated to each other in at least some embodiments. Thisinformation exchange may occur to enable each spine node to know theparameters of all other spines in the fabric. Based on this knowledge,each spine can use the same sharding algorithm to independently divide akey space into shard intervals based on the same parameters. Thisensures the resulting shard mapping to be in sync across the entirefabric.

At 506, spine node 20(1) applies a sharding algorithm to a key space(e.g., 32-bit) to divide the key space into shard intervals based onstatic and/or dynamic parameters of the spines and on the total numberof spines in the network fabric. The number of resulting primary shardintervals can equal the total number of spine nodes in network fabric15. Thus, one primary shard interval can be generated for each spinenode. In at least one embodiment, the total number of spine nodes isintended to include operational spine nodes. Therefore, if a spine nodehas a fault state parameter indicating the spine node is no longeroperational, then a shard interval may not be generated for that spinenode.

Each primary shard interval can be generated based, at least in part, onstatic parameters (e.g., capacity) and possibly dynamic parameters(e.g., load). For example, the capacities of spine nodes 20 are staticparameters that can be used to determine the proportion of the key spaceto be allocated for and assigned to each spine node as previouslydescribed herein. Dynamic parameters, such as a current load of a spine,may also be considered in some scenarios. For example, if spine node20(1) has a load that is above a certain threshold load, then themaximum number of endpoints allowed by the spine node's capacity may beadjusted downwardly so that a smaller proportion of key space isallocated for and assigned to spine node 20(1). This may be done toenable spine node 20(1) to operate more efficiently.

In one example, particular ranges for the shard intervals in the keyspace can be determined by assigning the shard intervals to spine nodes20 in numerical sort order of their tunnel endpoint IP (TEP IP)addresses. Spine node 20(1) can determine the particular range of thekey space for its own primary and backup shard intervals. Spine node20(1) may also determine the particular range of the key space for theother shard intervals assigned to the other spines.

At 508, the sharding algorithm of spine node 20(1) calculates one ormore backup shard intervals for each of the spines based on areplication factor, #R. The replication factor #R could be configuredfor network fabric 15 by a user or determined automatically (e.g.,default replication factor, network policies, tenant policies). In atleast one embodiment, each spine can be the backup owner of #R shards.Also, the size of each backup shard for a particular spine can be thesame size as the primary shard of that spine.

In at least one embodiment, flow 500 (or portions thereof) may beperformed by each spine in a network fabric to independently divide akey space and determine primary and backup shard intervals for all ofthe spines in the fabric, including the particular ranges within the keyspace associated with the intervals. Each spine can store the resultinginformation in its own shard mapping table. It will be apparent,however, that numerous other implementations may be possible. Forexample, only a selected one or more spines may perform the shardingalgorithm and then communicate the results to the other spines. Inanother example, one or more separate computing devices that are notconfigured as spines in the network fabric may perform the shardingalgorithm and then communicate the results to the spines. If yet anotherexample, each spine may calculate its own shard intervals (e.g., primaryand backup) and then each spine may communicate this information to theother spines in the network fabric. These alternative possibleimplementations are offered merely for illustrative purposes and are notintended to limit the broad teachings of this disclosure. Furthermore,it should be appreciated that any number of other configurations andpermutations may be implemented using the concepts of partialreplication disclosed herein.

Turning to FIG. 6, a flow 600 illustrates one or more possibleoperations that may be performed by spine nodes 20 of FIGS. 1 and 2, inwhich spine nodes 20 learn routing information of endpoints attached tonetwork fabric 15. Spine nodes 20 may comprise means, including forexample, processors 29, for performing such operations. In at least oneembodiment, endpoint synchronization protocol 22 of spine nodes 20 canbe used to perform, when executed by a processor, one or more of theoperations.

At 602, spine node 20(1) receives an advertisement from leaf node 30(1)containing routing information for endpoint 40(1). Spine node 20(1) mayreceive this advertisement from leaf node 30(1) when, for example, leafnode 30(1) learns of endpoint 40(1). In another possible scenario, spinenode 20(1) may receive this advertisement from another spine node if,for example, the other spine node is forwarding the advertisement itreceived from leaf node 30(1). At 604, spine node 20(1) generates a keyfor endpoint 40(1). In one example, the key can be generated by applyinga hashing algorithm to a BD and MAC address associated with theendpoint, or to a VRF and IP address associated with the endpoint. Thehashing algorithm can hash the BD and MAC address or VRF and IP addressinto a 32-bit key space in at least one embodiment.

At 606, spine node 20(1) can determine, based on the key, which spinenode in network fabric 15 owns routing information for endpoint 40(1).This may be determined by querying shard mapping table 23(1) of spinenode 20(1) to identify a shard interval that includes the key, and toidentify a spine node mapped to the identified shard interval. If therouting information is owned by spine node 20(1), as determined at 608,then at 610, endpoint repository 25(1) can be populated with the routinginformation for endpoint 40(1). However, if spine node 20(1) does notown the routing information as determined at 608, then at 612, spinenode 20(1) can forward the endpoint routing information of endpoint40(1) to the spine node identified from querying the shard mappingtable. The endpoint routing information should be forwarded to thespines owning the primary and backup shards.

Turning to FIG. 7, a flow 700 illustrates one or more possibleoperations that may be performed by spine nodes 20 of FIGS. 1 and 2,when spine nodes 20 receive network traffic from a leaf node in networkfabric 15. Spine nodes 20 may comprise means, including for example,processors 29, for performing such operations. In at least oneembodiment, endpoint proxy modules 26 of spine nodes 20 can be used toperform, when executed by a processor, one or more of the operations.

At 702, spine node 20(1) receives network traffic from leaf node 30(1)in network fabric 15. This traffic can be unknown unicast traffic beingsent from endpoint 40(1), which is connected behind leaf node 20(1), toa destination endpoint connected behind a different leaf node in network10. At 704, spine node 20(1) generates a key for the destinationendpoint. In one example, the key can be generated by applying a hashingalgorithm to a BD and MAC address associated with the destinationendpoint, or to a VRF and IP address associated with the destinationendpoint. The hashing algorithm can hash the BD and MAC address or VRFand IP address into a 32-bit key space in at least one embodiment.

At 706, spine node 20(1) can determine, based on the key, which spinenode in network fabric 15 owns routing information for the destinationendpoint. This may be determined by querying shard mapping table 23(1)of spine node 20(1) to identify a shard interval that includes the key,and to identify a spine node mapped to the identified shard interval. Ifthe routing information is owned by spine node 20(1), as determined at708, then spine node 20(1) can look up routing information for thedestination endpoint (e.g., in endpoint repository 25(1), in hardwarerouting table in TCAM). At 710, spine node 20(1) can forward the unknownunicast traffic according to the routing information. However, if spinenode 20(1) does not own the routing information as determined at 708,then at 712, spine node 20(1) can forward the unknown unicast traffic tothe spine node identified from querying the shard mapping table.

In FIG. 8, a flow 800 illustrates one or more possible operations thatmay be performed by leaf nodes 30 of FIGS. 1 and 2, when leaf nodes 30receive unknown unicast network traffic from an attached endpoint. Leafnodes 30 may comprise means, including for example, processors 39, forperforming such operations. In at least one embodiment, forwardingmodules 34 of leaf nodes 20 can be used to perform, when executed by aprocessor, one or more of the operations.

At 802, leaf node 30(1) receives unknown unicast traffic from anattached endpoint, such as endpoint 40(1), where the traffic is en routeto a destination endpoint attached to another leaf node in networkfabric 15. At 804, leaf node 30(1) generates a key for the destinationendpoint. In one example, the key is can be generated by applying ahashing algorithm to a BD and MAC address associated with thedestination endpoint, or to a VRF and IP address associated with thedestination endpoint. The hashing algorithm can hash the BD and MACaddress or VRF and IP address into a 32-bit key space in at least oneembodiment.

At 806, leaf node 30(1) attempts to determine, based on the key, whichspine node in network fabric 15 owns routing information for thedestination endpoint. This may be determined by querying shard mappingtable 33(1) of leaf node 30(1) to identify a shard interval thatincludes the key, and to identify a spine node mapped to the identifiedshard interval. If shard mapping information was previously propagatedto leaf node 30(1) from spine nodes 20, then shard mapping table 33(1)can enable identification of the appropriate spine node. If a spine nodeis identified in the query as determined at 808, then at 810, leaf node30(1) can forward the unknown unicast traffic to the identified spinenode. If however, a spine node was not identified in the query, then at812, the unknown unicast traffic may be forwarded to any one of thespine nodes.

Variations and Implementations

Note that in certain example implementations, the partial replicationfunctions outlined herein may be implemented by logic encoded in one ormore tangible media (e.g., embedded logic provided in an applicationspecific integrated circuit (ASIC), digital signal processor (DSP)instructions, software (potentially inclusive of object code and sourcecode) to be executed by a processor or other similar machine,instructions in software, hardware, firmware, or any combinationthereof, etc.). This tangible media may be non-transitory in at leastone embodiment. In some of these instances, one or more memory elements(as shown in FIGS. 1-2) can store data used for the operations describedherein. This includes the memory elements being able to store software,logic, code, and/or processor instructions that are executed to carryout the activities described herein. A processor can execute any type ofinstructions associated with the data to achieve the operations detailedherein. In one example, a processor (as shown in FIGS. 1 and 2) couldtransform an element or an article (e.g., data) from one state or thingto another state or thing. In another example, the activities outlinedherein may be implemented with fixed logic or programmable logic (e.g.,software/computer instructions executed by a processor) and the elementsidentified herein could be some type of a programmable processor,programmable digital logic (e.g., a field programmable gate array(FPGA), an erasable programmable read only memory (EPROM), anelectrically erasable programmable ROM (EEPROM)) or an ASIC thatincludes digital logic, software, code, electronic instructions, or anysuitable combination thereof.

In at least one example implementation, embodiments of spine and leafnodes of a network fabric may include logic in order to achieve thepartial replication functions outlined herein. These activities can befacilitated by various modules and protocols (e.g., endpointsynchronization modules 22, 32, negotiation modules 24, endpoint proxymodules 26, forwarding modules 34), which can be suitably combined inany appropriate manner, or partitioned in any appropriate manner, andwhich may be based on particular configuration and/or provisioningneeds. Additionally, these network elements may include one or moreprocessors (e.g., processors 29, 39) that can execute software, analgorithm, or other instructions to perform the partial replicationfunctions, as disclosed herein. These network elements may further keepinformation, to be used in achieving the partial replication activitiesas discussed herein, in any suitable memory element (random accessmemory (RAM), read only memory (ROM), EPROM, EEPROM, ASIC, TernaryContent-Addressable Memory (TCAM), etc.), software, hardware, or in anyother suitable component, device, element, or object where appropriateand based on particular needs. Any of the memory items discussed herein(e.g., repositories, caches, stores, databases, tables, etc.) should beconstrued as being encompassed within the broad term ‘memory element.’Similarly, any of the potential processing elements, modules, andmachines described in this Specification should be construed as beingencompassed within the broad term ‘processor.’ Each of the networkelements can also include suitable interfaces for receiving,transmitting, and/or otherwise communicating data or information in anetwork environment.

Note that with the examples provided herein, interaction may bedescribed in terms of two, three, or more network elements. However,this has been done for purposes of clarity and example only. In certaincases, it may be easier to describe one or more of the functionalitiesof a given set of flows by only referencing a limited number of networkelements. It should be appreciated that network fabric 15 and itsteachings are readily scalable and can accommodate a large number ofcomponents, as well as more complicated/sophisticated arrangements andconfigurations. For example, a system for providing partial replicationof endpoint routing information can be implemented in multiple fabricpods connected to each other. Accordingly, the examples provided shouldnot limit the scope or inhibit the broad teachings of the partialreplication system as potentially applied to a myriad of otherarchitectures or implementations.

As used herein, unless expressly stated to the contrary, use of thephrase ‘at least one of’ refers to any combination of the namedelements, conditions, or activities. For example, ‘at least one of X, Y,and Z’ is intended to mean any of the following: 1) X, but not Y and notZ; 2) Y, but not X and not Z; 3) Z, but not X and not Y; 4) X and Y, butnot Z; 5) X and Z, but not Y; 6) Y and Z, but not X; or 7) X, Y, and Z.Additionally, unless expressly stated to the contrary, the terms‘first’, ‘second’, ‘third’, etc., are intended to distinguish theparticular nouns (e.g., element, condition, module, activity, operation,etc.) they modify. The use of these terms is not intended to indicateany type of order, rank, importance, temporal sequence, or hierarchy ofthe modified noun. For example, ‘first X’ and ‘second X’ are intended todesignate two separate X elements that are not necessarily limited byany order, rank, importance, temporal sequence, or hierarchy of the twoelements.

It is also important to note that the activities, interactions, andoperations in the preceding flow diagrams illustrate only some of thepossible partial replication scenarios and patterns that may be executedby, or within, embodiments of a system for partially replicationendpoint routing information. Some of these activities, interactions,and/or operations may be deleted or removed where appropriate, or may bemodified, divided, or changed considerably without departing from thescope of the present disclosure. In addition, a number of theseactivities, interactions, and/or operations have been described as beingexecuted before, after, concurrently with, or in parallel to, one ormore additional activities, interactions, and/or operations. However,the timing of these activities, interactions, and/or operations may bealtered considerably. The preceding operational flows have been offeredfor purposes of example and discussion. Substantial flexibility isprovided by the partial replication system in that any suitablearrangements, chronologies, configurations, and timing mechanisms may beprovided without departing from the teachings of the present disclosure.

Although the present disclosure has been described in detail withreference to particular arrangements and configurations, these exampleconfigurations and arrangements may be changed significantly withoutdeparting from the scope of the present disclosure. Moreover, certaincomponents may be combined, separated, eliminated, or added based onparticular needs and implementations. Additionally, although networkfabric 15 has been illustrated with reference to particular elements andoperations that facilitate the communication process, these elements andoperations may be replaced by any suitable architecture, protocols,and/or processes that achieve the intended functionality of networkfabric 15.

What is claimed is:
 1. A method, comprising: calculating a first shardinterval of a key space based, at least in part, on capacities of aplurality of spine nodes in a leaf-spine network fabric; mapping thefirst shard interval to a first spine node of the plurality of spinenodes, each of the plurality of spine nodes mapped to one or more shardintervals; communicating shard mapping information associated with themapping to a set of leaf nodes in the network fabric; populating anendpoint repository in the first spine node with routing information forone or more endpoints corresponding to the first shard interval; andcalculating one or more backup shard intervals based on a configurablereplication factor, the one or more backup shard intervals includingeach key of the first shard interval, the configurable replicationfactor indicating a number of backup shards that each of the pluralityof spine nodes owns.
 2. The method of claim 1, further comprising:determining a capacity of the first spine node; and receiving capacityinformation indicating one or more other capacities for one or moreother spine nodes of the plurality of spine nodes.
 3. The method ofclaim 1, wherein the calculating the first shard interval of the keyspace is based, in part, on one or more dynamic parameters of at leastone spine node in the plurality of spine nodes.
 4. The method of claim1, further comprising: receiving, at the first spine node, a packet enroute to a destination endpoint; and identifying, if the destinationendpoint does not correspond to the first shard interval, a second spinenode mapped to a second shard interval, the destination endpointcorresponding to the second shard interval; and forwarding the packet tothe second spine node.
 5. The method of claim 1, wherein a hashingalgorithm applied to a unique identifier of any one of the one or moreendpoints corresponding to the first shard interval generates a key thatis included in the first shard interval.
 6. The method of claim 1,further comprising: calculating one or more other shard intervals foreach one or more other spine nodes of the plurality of spine nodesbased, at least in part, on the capacities of the plurality of spinenodes.
 7. The method of claim 6, wherein the first shard interval andthe one or more other shard intervals are assigned to the plurality ofspine nodes in numerical sort order of tunnel endpoint Internet Protocol(IP) addresses of the plurality of spine nodes.
 8. The method of claim1, further comprising: mapping at least one backup shard interval to thefirst spine node, wherein the at least one backup shard intervalincludes at least a portion of another shard interval mapped to anotherspine node.
 9. The method of claim 8, wherein each key of the firstshard interval is included in one or more backup shard intervals mappedto one or more other spine nodes based on the replication factor. 10.The method of claim 1, wherein the shard mapping information iscommunicated out of band to the set of leaf nodes in the network fabric.11. The method of claim 1, further comprising: dynamically recalculatingthe first shard interval to determine an updated first shard intervalbased on the capacities of the plurality of spine nodes and one or moredynamic parameters of at least one spine node of the plurality of spinenodes.
 12. The method of claim 11, wherein the one or more dynamicparameters include a load of one or more of the plurality of spinenodes.
 13. At least one non-transitory, machine readable storage mediumcomprising instructions that, when executed by a processor, cause theprocessor to: calculate a first shard interval of a key space based, atleast in part, on capacities of a plurality of spine nodes in aleaf-spine network fabric; map the first shard interval to a first spinenode of the plurality of spine nodes, each of the plurality of spinenodes mapped to one or more shard intervals; communicate shard mappinginformation associated with the mapping to a set of leaf nodes in thenetwork fabric; populate an endpoint repository in the first spine nodewith routing information for one or more endpoints corresponding to thefirst shard interval; and calculate one or more backup shard intervalsbased on a configurable replication factor, the one or more backup shardintervals including each key of the first shard interval, theconfigurable replication factor indicating a number of backup shardsthat each of the plurality of spine nodes owns.
 14. The medium of claim13, wherein mapping the first shard interval to the first spine nodeincludes populating a shard mapping table with the shard mappinginformation.
 15. The medium of claim 13, wherein the instructionsfurther cause the processor to dynamically recalculate the first shardinterval to determine an updated first shard interval based on thecapacities of the plurality of spine nodes and one or more dynamicparameters of at least one spine node of the plurality of spine nodes.16. The medium of claim 15, wherein the one or more dynamic parametersinclude at least one of a load of the at least one spine node and afault state of one or more of the spine nodes.
 17. An apparatuscomprising: at least one memory element having instructions storedtherein; and at least one processor, wherein the instructions whenexecuted by the at least one processor, cause the processor to:calculate a first shard interval of a key space based, at least in part,on capacities of a plurality of spine nodes in a leaf-spine networkfabric; map the first shard interval to a first spine node of theplurality of spine nodes, each of the plurality of spine nodes mapped toone or more shard intervals; communicate shard mapping informationassociated with the mapping to a set of leaf nodes in the networkfabric; populate an endpoint repository in the first spine node withrouting information for one or more endpoints corresponding to the firstshard interval; and calculate one or more backup shard intervals basedon a configurable replication factor, the one or more backup shardintervals including each key of the first shard interval, theconfigurable replication factor indicating a number of backup shardsthat each of the plurality of spine nodes owns.
 18. The apparatus ofclaim 17, wherein the first shard interval is calculated based, in part,on one or more dynamic parameters of at least one spine node of theplurality of spine nodes.
 19. The apparatus of claim 17, wherein ahashing algorithm applied to a unique identifier of any one of the oneor more endpoints corresponding to the first shard interval is togenerate a key that is included in the first shard interval.
 20. Theapparatus of claim 17, wherein, the instructions further cause theprocessor to map the one or more backup shard intervals to the firstspine node, and the one or more backup shard intervals include at leasta portion of another shard interval mapped to another spine node.